On 2/18/2014 12:22 PM, Marc Perkel wrote:
Trying to do something complex and not sure how it's done. What I'm
looking for is to combine 2 conditions in a single regular expression
so that both have to be true for a match. Yes - I know I can make 2 SA
rules and combine them but I bet there's a way to do it in one
expression. For simplicity here's the challenge.
A chuck of text has to include the word "cat" 5 time and the word
"dog" 4 times to be a match. How do you do that?
Take the FSM approach. You have thirty states to deal with, specifically
{found X dogs, Y cats | X <- {0..5}, Y <- {0..4}}. The transitions
between states should be obvious. Naively translating to a regex, you
get a very very long pattern.
http://cs.stackexchange.com/questions/2016/how-to-convert-finite-automata-to-regular-expressions
As John alludes to, though it is technically possible you really don't
want to do this. There's much more maintainable and composable ways to
write what you need.
